Methods To Detect Organic Contaminants In Pulp and Fiber

ABSTRACT

A method to detect organic contaminants in pulp and fiber is described which uses hydrophobic dyes, such as fluorescent dyes.

This application claims the benefit under 35 U.S.C. §119(e) of prior U.S. Provisional Patent Application No. 60/930,414, filed May 16, 2007, which is incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to pulp and fiber and more particularly relates to methods to detect and/or quantify organic contaminants, such as microstickies, present in pulp and fiber.

Conventional recycling of old paper products such as old new print, old corrugated containers, and mixed office waste is an important aspect of papermills today due to environmental demands that many paper containing products have a portion of recycled fibers contained within the paper product. Thus, papermills are in a situation where the recycling of paper products is a necessity. However, the recycling of the paper products generally requires additional processing steps in order to lead to fibers which can be useable in paper products.

Conventional recycling of old newspapers to obtain fibers comparable to the type of fibers used to originally make the newsprint is known in the art as “de-inking,” and typically involves pulping, washing, usually with surfactants, screening, solubilizing insoluble contaminants usually by strong caustic treatments, washing, and bleaching of the fibers to counteract the yellowing effects of caustic treatments.

Generally, the first step in conventional recycling is to separate the paper into individual fibers with water to form a pulp slurry followed by removing ink and contaminants from the fibers by a combination of various process steps, such as screening, centrifugal cleaning, washing, flotation, and the like The screening and centrifugal cleaning step removes large contaminants, such as paperclips, staples, plastics, and the like. The primary purpose of washing and flotation steps is to solubilize and/or suspend contaminants in the water and to remove the contaminants from the water. Surfactants and caustic agents are added to facilitate the solubilization and separation of contaminants from the fibers. Once caustic agents are used, some yellowing of the fibers occurs which results in a need to bleach the fibers. The fibers are blended with, typically, virgin fibers and then used in the papermaking process for which the fiber properties are suitable. Recent developments in waste paper de-inking make use of enzymes to aid in the detachment and removal of inks from the fibers. These processes describe the use of particular types of enzymes to facilitate ink removal without the negative effects of caustic treatment on brightness along with the use of flotation to remove the agglomerated ink particles.

In the past, chemical additives such as caustic agents have been added to remove organic contaminants, known as “stickies.” Stickies are generally adhesives, glues, hot melts, coatings, coating binders, ink residues, de-inking chemicals, wood resins, rosin, and unpulped wet strength resins that typically are present with the fiber to be recycled. These organic contaminants typically must be removed in substantial quantities so that they do not affect the subsequent processing steps. There is always a desire in the papermaking industry to develop new methods to remove such organic contaminants in more effective and environmentally friendly ways.

“Stickies” can be generally described as tacky, hydrophobic, pliable organic materials found in recycled paper systems. Stickies have a broad range of melting points and different degrees of tackiness dependent upon the composition of the stickies. Temperature, pH, concentration, size, and composition can affect the tackiness of stickies.

Recycled paper fibers contain many components that when repulped in recycle fiber plants become stickies. Recycled furnishes may have as many as a dozen different types of stickies, each having its own characteristics. Sources of stickies may include any of the following: adhesives, hot melts, coating binders, ink residues, deinking chemicals, wood resins, rosin, pitch, and wet strength resins. The actual tacky deposits found on paper machines may be a combination of several of these organic contaminants as well as inorganic particles such as talc, clay, or calcium carbonate.

Stickies deposit on machine surfaces, fabrics, wires, felts, and rolls and lead to problems such as wet end breaks, pressroom breaks, dryer section breaks, holes, sheet defects, and high dirt counts. These deposits and associated problems lead to a significant amount of downtime yearly. The cost of stickies has been estimated at over 500 million dollars annually in the U.S., when considering the cost of downtime, chemical costs, production losses, rejected materials, and customer complaints.

There are typically two main methods of removing stickies, mechanical and chemical. Mechanical methods include screening, cleaning, washing, floating, and disperging, with each method designed to remove a different size contaminant. Screening typically removes larger or macro stickies (>0.004 inch or >100 microns). Forward and reverse cleaners can be used. Based on density differences using centrifugal force, forward cleaners remove contaminants heavier than water and reverse cleaners remove particles lighter than water. This method removes more macro stickies than micro stickies. Floating removes intermediate size stickies (50-300 microns), which are troublesome, because they're small enough to be accepted by screening and cleaning but too large to be removed by washing. In disperging, the stock is thickened, passed through a device at high temperature, pressure, and shear, which breaks organic contaminants, including stickies, into smaller pieces.

Various chemical methods can be used. For instance, in pacification, additives like talc, clay, nonionic organic polymers, and other inorganic particles are used to render the stickies less tacky. In dispersion, dispersants, surfactants, and solvents are used to make stickies smaller.

In fixation, the stickies are attached to the paper sheet by using a cationic water soluble polymer, which adds charge to the stickies. In disperse and fix, a dispersant is added first to reduce the size of the stickies and then a cationic polymer is used to fix the stickies onto the sheet. With passivation, the use of dispersants, solvents, and low molecular weight cationic polymers makes the paper machine less susceptible to stickies.

The favored approach to remove stickies is to keep the stickies large in the stock prep area, so that the mechanical cleaning equipment can remove as many “stickies” as possible. Then, all remaining stickies should be dispersed either mechanically or chemically and fixed to the fiber, so that it can be sent out with the sheet.

Once as many stickies as possible are removed mechanically, the rest have in the past been dispersed mechanically, chemically, or by using a combination of the two. Once dispersed, polymer addition to stabilize these particles in their smallest state has been used, so that the particles will be retained on the sheet.

Measuring and controlling stickies in a recycled paper manufacturing process has always been a challenge. Variations in recycled paper quality and the trend to increase the amount of waste paper incorporated into each ton of pulp produced are each contributing factors that make this challenge even more difficult to address. (Pulp and Paper Fact Book, 2000). These variations make predicting the amount of stickies that are entering a mill's system troublesome. Once these stickies are in the system, the larger contaminants, or macrostickies, are often removed mechanically. However, additional stresses on the screens and cleaner banks such as high furnish consistency, improper in-screen dilution, improper reject rates, and differential pressure control problems will facilitate the acceptance of formed macrostickies (Gallagher, 1997). Macrostickies are defined as stickies that are retained on a 0.10 mm (100 micron) screen plate (Heise, 1998). These contaminants which come from adhesives, coatings, binders, and other materials are incorporated into the furnish during the pulping process, and will deposit on forming fabrics, press felts, dryer fabrics, press section pick rolls, Uble boxes, and calendar stacks (Douek, 1997). These materials remain tacky in the papermaking process, leading to the “stickies” label (Doshi, 1997). Once the materials are incorporated into the fumish, they are difficult to remove, since they are deformable in nature and are often close to the specific gravity of water. These physical characteristics present a different screening and cleaning challenge as these contaminants slip through screens and cleaners (Scholz, 1997) that are designed to allow water and fiber to be accepted. The consequence of this fact is the acceptance of macrostickies into the post screening process.

Even if the cleaning and screening systems do perform properly and do remove most of the macrostickies, the remaining microstickies may cause problems. The agglomeration of microstickies, stickies not retained on a 0.1 mm (100 micron) screen, can lead to the formation of macrostickies which will then deposit onto the machine and onto fabric surfaces (Doshi, 1997).

The cost of stickies deposition is a significant one. One source estimates the cost of the stickies problem to the industry in terms of machine downtime to be over $500 million annually for major recycled paper grades (Friberg, 1997). Once macrostickies are present in the furnish after the screening and cleaning systems, mechanical means of removing stickies have been exhausted. Preventing the agglomeration of microstickies is also an issue in addition to the microstickies problem.

There have been some techniques in the past to monitor or determine if organic contaminants, and especially microstickies, are present in the paper manufacturing process. However, most, if not all, of these tests are time-consuming, inaccurate, provide false-positive readings, are difficult to use in the mill, are not based on real time testing, and the like. It would be important to papermills to have a method to detect and/or quantify organic contaminants, especially microstickies, present in paper manufacturing processes so that appropriate action can be taken to control the organic contaminants present and/or determine whether current treatments are satisfactorily controlling organic contaminants in pulp and fiber. It would be beneficial to have a method that can do this on a real time basis and can do so in a quick and economic manner and further be able to do so in an accurate manner.

SUMMARY OF THE PRESENT INVENTION

A feature of the present invention is to provide methods to detect organic contaminants, e.g., microstickies, in pulp and fiber.

A further feature of the present invention is to provide methods to quantify organic contaminants present in pulp and fiber.

A further feature of the present invention is to provide methods to detect and/or quantify organic contaminants present in pulp and fiber on a real time basis.

An additional feature of the present invention is to provide a method to detect and/or quantify organic contaminants in pulp and fiber which provides an accurate reading and can be conducted at the papermill site.

Additional features and advantages of the present invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention will be realized and attained by means of the elements and combinations particularly pointed out in the description and appended claims.

To achieve these and other advantages, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention relates, in part, to a method to detect organic contaminants in pulp and fiber. The method includes obtaining a sample of the pulp and fiber and contacting the sample with at least one hydrophobic dye, such as a fluorescent hydrophobic dye or other excitable hydrophobic dye, wherein the hydrophobic dye stains the organic contaminants present in the sample. After this staining, optionally, the amount of organic contaminants can be measured by placing the sample under a microscope and contacting the sample with an appropriate energy source to excite the hydrophobic dye that may be present so that the organic contaminants are readily seen from amongst the pulp and fiber and other non-organic contaminant material. By doing so, the size of the contaminants, surface area of the contaminants, number of contaminants, and any other determination that can be made from observation can be determined.

The present invention further relates to organic contaminants in pulp and fiber with at least one hydrophobic dye that stains organic contaminants present in the pulp and fiber without staining the pulp and fiber.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide a further explanation of the present invention, as claimed.

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate some of the embodiments of the present invention and together with the description, serve to explain the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a microphotograph showing organic contaminants that have been stained with a fluorescent dye and which are present amongst pulp and fiber which have not been stained.

FIG. 2 is a graph with plots of Krofta feed and accepts microstickies data measured in tests conducted in a paper production facility as described in the examples set forth hereinafter.

FIG. 3 is a graph with plots of paper machine (PM) headbox and PM whitewater (WW) microstickies data measured in tests conducted in a paper production facility as described in the examples set forth hereinafter.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates, in part to methods to detect organic contaminants in pulp and fiber. The present invention further relates to pulp and fiber containing organic contaminants, wherein the organic contaminants have been stained with at least one hydrophobic dye, and optionally wherein the pulp and fiber themselves have not been stained.

The present invention further relates to methods to quantify and/or otherwise analyze one or more characteristics of the organic contaminants present in pulp and fiber using one or more hydrophobic dyes.

For purposes of the present invention, examples of organic contaminants include what is known in the industry as “stickies” and include, but are not limited to, synthetic polymers resulting from adhesives and the like, glues, hot melts, coatings, coating binders, ink residues, de-inking chemicals, wood resins, rosin, and unpulped wet strength resins.

These types of materials are typically found in paper containing products, such as newsprint, corrugated container, and/or mixed office waste. These organic contaminants typically will have polymers (e.g., thermoplastic(s)) present, such as styrene butadiene rubber, vinyl acrylates, polyisoprene, polybutadiene, natural rubber, ethyl vinyl acetates, polyvinyl acetates, ethylvinyl alcohols, polyvinyl alcohols, styrene acrylates, and/or other synthetic type polymers.

As stated above, for purposes of the present invention, microstickies are typically stickies having a particle size above 100 microns and microstickies are considered organic contaminant particles having a particle size of 100 microns or less (e.g., 10 microns to 100 microns). The present invention is especially useful in detecting microstickies in pulp and fiber since, typically, microstickies can be effectively removed, as discussed above, using mechanical and/or chemical techniques. It would be quite beneficial to be able to detect and know information regarding the organic contaminants present in pulp and fiber, and especially microstickies, so as to assist a papermill in determining proper treatments, treatment levels, and/or whether treatment should be initiated or not based on the amount of microstickies present. Needless to say, these types of determinations should be made on a real time basis, or the papermill will simply have to assume that a certain number of organic contaminants, especially microstickies, are present in the papermill irrespective of whether those organic contaminants are really present or not as a safety precaution. The present invention permits a papermill to be able to detect organic contaminants, especially microstickies, on a real time basis, thus permitting the papermill to tailor the treatment of microstickies based on real information, and/or to adjust treatment levels based on the amount of stickies present, which can save the papermill significant amounts of money, chemicals, and increase the efficiency of the papermill plant.

In one or more embodiments of the present invention, the present invention relates to a method to detect organic contaminants in pulp and fiber. The method includes the step of obtaining a sample of the pulp and fiber and then contacting this sample with at least one hydrophobic dye, wherein the hydrophobic dye stains the organic contaminants present in the sample. Preferably, the hydrophobic dye does not stain the pulp and fiber present in the sample or at least does not significantly stain the pulp and fiber such that the staining of the organic contaminants is clearly distinguishable from the pulp and fiber.

The pulp and fiber can be any pulp and fiber that is used in a papermill. The pulp and fiber can be virgin, recycled, or a blend of the two. The fiber is typically cellulose fibers and more typically includes recycled fibers from one or a variety of paper products or fiber containing products, such as old corrugated containers (OCC), old newsprint (ONP), mixed office waste (MOW), or combinations thereof. These types of paper containing products typically contain large amounts of organic contaminants which are present in the paper products. When these types of paper products are recycled, these organic contaminants are present along with the fibers formed during the pulping stage of a papermaking process. These organic contaminants, if not substantially removed, can severely interfere with subsequent stages in the papermaking process by affecting the quality of the resulting sheets of paper formed and/or affecting the machinery used to form the paper. Accordingly, the removal of such organic contaminants is important to the paper making process when such organic contaminants are present in fibers.

With respect to obtaining a sample, the sample of the pulp and fiber can be obtained at any stage (or multiple stages) of the papermaking process. For instance, the sample can be obtained prior to any mechanical or chemical treatment to control organic contaminants. The sample can be obtained during any mechanical or chemical treatment, after treatment, or at any other stage of the papermaking process. There is no limit as to where the sample can be taken from the papermaking process. With respect to the amount of the sample, any amount of the pulp and fiber sample can be used, such as from about 10 to about 30 oven dried grams of fiber (if pulp slurry) or about 1 to about 200 grams water-based samples (i.e., whitewater/process water, Uhle box discharge, washer, press filtrates (low fiber containing samples)). The size of the sample is not critical to the method of the present invention. In determining the amount or concentration of organic contaminants present it would be helpful to know the amount of the sample being tested.

Once a sample is taken, the sample is contacted with at least one hydrophobic dye. The hydrophobic dye is preferably a fluorescent dye or a dye that is otherwise excitable such that is emits radiation which can be detected. Preferably, the hydrophobic dye is a fluorescent hydrophobic dye or a dye that emits visible radiation, but UV detectable or infrared detectable dyes can also be used.

Examples of hydrophobic dyes that can be used include, but are not limited to, the following: Quinoline Dye (Naphthalimide) (e.g., Morplas Fluorescent Yellow G Powder, syn: Solvent Yellow 43)); Anthraquinone (e.g., Morplas Red 46 Powder, syn: Solvent Red 168, and Morplas Blue 1003. Powder, syn: Solvent Blue 36); Coumarin (e.g., Navipal SWNR Powder, Fluorescent Brightener 140, and Ranipal SWNR Powder). Each of these are available from Sunbelt Corporation. Other examples include TRY 53 Tracer Yellow Dye and TRY-33 Tracer Yellow Dye Solution from Day-Glo Color Corporation.

Also, hydrophobic dyes of the Sudan group can be used, such as Oil Red O, Sudan III, Sudan W, or Sudan black B. Other examples include Nile Red, which is a phenoxazone dye. Other examples include dyes from Orco and including the Orcoplast® group of dyes, which include fluorescent dyes. Other dyes that can be used that are hydrophobic dyes include dyes from New Dragon Co., Ltd., which include fluorescent dyes. Fluorescent dyes having an aminostyryl and quinolinium moieties can be used. These dyes are also known as fluorescent aminostyryl quinolinium dyes. Other fluorescent hydrophobic dyes that can be used include 1-anilinonaphthalene-8-sulfonic acid (ANS) and 1,6-diphenyl-1,3,5-hexatriene (DPH).

The amount of the hydrophobic dye used in the present invention can be any amount sufficient to stain the organic contaminants present in the pulp and fiber sample. Preferably, the dye is diluted or dissolved in an appropriate solvent, such as an organic solvent, like propylene glycol. Other examples of organic solvents that can be used include, but are not limited to, methylcarbitol, methylpyrrolidone, tetrahydrofuran, dipropylene glycol monoethyl ether, butanol, acetone, and alcohol. Tetrahydrofuran can come as an acetic anhydride, and the butanol, alcohol, and acetone particularly may be in anhydrous form. It is desired that the hydrophobic dye is one which dissolves in an organic solvent for the preparation of the dispersion in an amount of at least 2 g/L, preferably 20 to 500 g/L at 25° C. from the viewpoint of efficiently containing the hydrophobic dye.

Suitable solvents can be selected based on their ability to solubilize the particular class of hydrophobic dyes of interest. It is preferable that their solubility characteristics are substantially similar. The solvents can be acyl, aliphatic, cycloaliphatic, aromatic or heterocyclic hydrocarbons; the solvents may or may not have halogens, oxygen, sulfur, nitrogen, and/or phosphorous as either terminal groups or as integral parts of a ring or chain. Specifically, solvents such as toluene, xylene, hexane, pentane, acetone, DMSO, or methylene chloride can be used. Chlorinated solvents, such as chloroform, can be used. For instance, one gram of dye can be combined with 100 mls of organic solvent such as propylene glycol, to create an appropriate solution which then can be used in staining the organic contaminants present in the pulp and fiber sample. Generally, the amount of dye that can be used is from about 100 ppm to about 1% by weight (or more) of dye which is present in solution with at least one organic solvent in an amount to achieve these concentration levels. The dye can be present in a solvent in an amount of 1000 ppm to about 1% by weight of the overall solution containing the dye.

Examples of the hydrophobic dye include oil-soluble dyes, disperse dyes and the like. The oil-soluble dyes are not limited to specified ones, and include, for instance, C.I. Solvent Black 3, 7, 27, 29 and 34; C.I. Solvent Yellow 14, 16, 29, 56 and 82; C.I. Solvent Red 1, 3, 8, 18, 24, 27, 43, 51, 72 and 73; C.I. Solvent Violet 3; C.I. Solvent Blue 2, 11 and 70; C.I. Solvent Green 3 and 7; C.I. Solvent Orange 2; C.I. Disperse Yellow 5, 42, 54, 64, 79, 82, 83, 93, 99, 100, 119, 122, 124, 126, 160, 184:1, 186, 198, 199, 204, 224 and 237; C.I. Disperse Orange 13, 29, 31:1, 33, 49, 54, 55, 66, 73, 118, 119 and 163; C.I. Disperse Red 54, 60, 72, 73, 86, 88, 91, 93, 111, 126, 127, 134, 135, 143, 145, 152, 153, 154, 159, 164, 167:1, 177, 181, 204, 206, 207, 221, 239, 240, 258, 277, 278, 283, 311, 323, 343, 348, 356 and 362; C.I. Disperse Violet 33; C.I. Disperse Blue 56, 60, 73, 87, 113, 128, 143, 148, 154, 158, 165, 165:1, 165:2, 176, 183, 135, 197, 198, 201, 214, 224, 225, 257, 266, 267, 287, 354, 358, 365 and 368; C.I. Disperse Green 6:1 and 9; and the like.

In one embodiment, one or more fluorescent dyes can be used, such as squaraine, e.g., red dye which can be 1,3-bis[(1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)methyl]-2,4-dihydroxy-cyclobutenediylium, bis(inner salt) and an orange dye can be 2-(3,5-dimethylpyrrol-2-yl)-4-(3,5-dimethyl-2H-pyrrol-2-ylidene)-3-hydroxy-2-cyclobuten-1-one. The molar ratio between first and second dye can be from about 0 to 10,000. Both dyes can be excited at the same absorption wavelength, e.g., ranging from ultraviolet to about 800 nm, and emit fluorescent light at two distinct, essentially non-overlapping wavelengths distant from each other by at least 10 nm, preferably 30 nm, and more preferably by at least 50 nm. For example, the emission peak of the dye #1 can be at 585 nm, and the peak emission of dye #2 can be at 630 nm.

The squaric acid based fluorescent dyes can be synthesized by methods described in the literature. See, for example, Sprenger et al. Angew. Chem., 79, 581 (1967); Angew. Chem., 80, 541 (1968); and Maaks et al., Angew Chem. Intern. Edit., 5, 888 (1966). Briefly, one equivalent of squaric acid (1,2-dihydroxycyclobutenedione) is condensed with two equivalents of an active compound, such as a pyrrole, indoline, or aniline, and refluxed in a mixture of an alcohol and an aromatic solvent (such as benzene) under conditions that allow removal of water from the reaction mixture. The resulting dye can be collected and purified by a number of standard methods, such as recrystallization, distillation, chromatography, etc. Additionally, unsymmetrically substituted squaric acid compounds can be synthesized by methods such as those described by Law et al., J. Org. Chem. 57, 3278, (1992). Specific methods of making such dyes are well known in the art and can be found for example in U.S. Pat. Nos. 5,795,981; 5,656,750; 5,492,795; 4,677,045; 5,237,498; and 5,354,873. Optionally such dyes can contain functional groups capable of forming a stable fluorescent product with functional groups including activated esters, isothiocyanates, amines, hydrazines, halides, acids, azides, maleimides, alcohols, acrylamides, haloacetamides, phenols, thiols, acids, aldehydes and ketones.

Related dyes can be used, such as cyclobutenedione derivatives, substituted cephalosporin compounds, fluorinated squaraine compositions, symmetrical and unsymmetrical squaraines, alkylalkoxy squaraines, or squarylium compounds. Some of these dyes can fluoresce at near infrared as well as at infrared wavelengths that would effectively expand the range of emission spectra up to about 1,000 nm.

In addition to squaraines, i.e., derived from squaric acid, hydrophobic dyes such as phthalocyanines and naphthalocyanines can be also selected as operating at longer wavelengths. Other classes of fluorochromes are equally suitable for use as dyes according to the present invention. Some of these dyes are listed herein: 3-Hydroxypyrene 5,8,10-Tri Sulfonic acid, 5-Hydroxy Tryptamine, 5-Hydroxy Tryptamine (5-HT), Acid Fuhsin, Acridine Orange, Acridine Red, Acridine Yellow, Acriflavin, AFA (Acriflavin Feulgen SITSA), Alizarin Complexon, Alizarin Red, Allophycocyanin, ACMA, Aminoactinomycin D, Aminocoumarin, Anthroyl Stearate, Aryl- or Heteroaryl-substituted Polyolefin, Astrazon Brilliant Red 4G, Astrazon Orange R, Astrazon Red 6B, Astrazon Yellow 7 GLL, Atabrine, Auramine, Aurophosphine, Aurophosphine 6, BAO 9 (Bisaminophenyloxadiazole), BCECF, Berberine Sulphate, Bisbenzamide, BOBO 1, Blancophor FFG Solution, Blancophor SV, Bodipy Fl, BOPRO 1, Brilliant Sulphoflavin FF, Calcien Blue, Calcium Green, Calcofluor RW Solution, Calcofluor White, Calcophor White ABT Solution, Calcophor White Standard Solution, Carbocyanine, Carbostyryl, Cascade Blue, Cascade Yellow, Catecholamine, Chinacrine, Coriphosphine O, Coumarin, Coumarin-Phalloidin, CY3.1 8, CY5.1 8, CY7, Dans (1-Dimethyl Amino Naphaline 5 Sulphonic Acid), Dansa Diamino Naphtyl Sulphonic Acid), Dansyl NH—CH3, DAPI, Diamino Phenyl Oxydiazole (DAO), Dimethylamino-5-Sulphonic acid, Dipyrrometheneboron Difluoride, Diphenyl Brilliant Flavine 7GFF, Dopamine, Eosin, Erythrosin ITC, Ethidium Bromide, Euchrysin, FIF (Formaldehyde Induced Fluorescence), Flazo Orange, Fluo 3, Fluorescamine, Fura-2, Genacryl Brilliant Red B, Genacryl Brilliant Yellow 10GF, Genacryl Pink 3G, Genacryl Yellow 5GF, Gloxalic Acid, Granular Blue, Haematoporphyrin, Hoechst 33258 (bound to DNA), Indo-1, Intrawhite Cf Liquid, Leucophor PAF, Leucophor SF, Leucophor WS, Lissamine Rhodamine B200 (RD200), Lucifer Yellow CH, Lucifer Yellow VS, Magdala Red, Marina Blue, Maxilon Brilliant Flavin 10 GFF, Maxilon Brilliant Flavin 8 GFF, MPS (Methyl Green Pyronine Stilbene), Mithramycin, NBD Amine, Nile Red, Nitrobenzoxadidole, Noradrenaline, Nuclear Fast Red, Nuclear Yellow, Nylosan Brilliant Flavin E8G, Oregon Green, Oxazine, Oxazole, Oxadiazole, Pacific Blue, Pararosaniline (Feulgen), Phorwite AR Solution, Phorwite BKL, Phorwite Rev, Phorwite RPA, Phosphine 3R, Phthalocyanine, Phycoerythrin R, Polyazaindacene Pontochrome Blue Black, Porphyrin, Primuline, Procion Yellow, Propidium Iodide, Pyronine, Pyronine B, Pyrozal Brilliant Flavin 7GF, Quinacrine Mustard, Rhodamine 123, Rhodamine 5 GLD, Rhodamine 6G, Rhodamine B, Rhodamine B 200, Rhodamine B Extra, Rhodamine BB, Rhodamine BG, Rhodamine WT, Rose Bengal, Serotonin, Sevron Brilliant Red 2B, Sevron Brilliant Red 4G, Sevron Brilliant Red B, Sevron Orange, Sevron Yellow L, SITS (Primuline), SITS (Stilbene Isothiosulphonic acid), Stilbene, Snarf 1, sulpho Rhodamine B Can C, Sulpho Rhodamine G Extra, Tetracycline, Texas Red, Thiazine Red R, Thioflavin S, Thioflavin TCN, Thioflavin 5, Thiolyte, Thiozol Orange, Tinopol CBS, TOTO 1, TOTO 3, True Blue, Ultralite, Uranine B, Uvitex SFC, Xylene Orange, XRITC, YO PRO 1, or combinations thereof. One skilled in the art would certainly know which one to select among such dyes as long as desired emission and absorption properties as well as their hydrophobic properties are appropriate. It is preferable that the dyes have higher solubility in organic solvents and have improved photostability and quantum yields.

In one or more embodiments of the present invention, the present invention thus involves or includes a pulp and fiber sample that contains organic contaminants wherein the organic contaminants are stained with at least one hydrophobic dye and preferably at least one hydrophobic fluorescent dye. The amount of dye present in the staining can be based on the amounts previously provided.

A method for determining fluorescence in accordance with the present invention can involve the use of the fiber optic cytometer, for instance, as described in U.S. Pat. No. 4,564,598, the disclosure of which is incorporated herein in its entirety. An optical fiber is used to define a relatively small volume from which fluorescent light can be received and counted. The volume is related to the volume in which there is likely to be one or relatively few particles which produce predetermined fluctuations. By employing any one of several mathematical techniques for fluctuation analysis, the fluorescence fluctuations are related to the presence of an analyte in a sample. The fluctuations are observed over a period of time in a static mode or preferably by sampling a plurality of volumes in the sample. By comparing the observed results with results obtained with samples or calibrators known to be free of analyte and other samples or calibrators known to contain the analyte, the presence or absence of analyte in unknown samples can be determined.

The contacting of the sample with at least one hydrophobic dye can be done in any manner in which a dye is used to stain an object. For instance, an eyedropper can be used, a pipette can be used, a spray bottle can be used, a beaker can be used, and a titration apparatus can be used. There are no limitations with respect to the manner in which one can contact the dye with the pulp and fiber sample.

Once the sample has been contacted with the hydrophobic dye, the sample can then be analyzed for determining if organic contaminants are present, whether the organic contaminants are microstickies, and other characteristics of the organic contaminants, such as surface area, amount, and the like. This analysis can be done, as an option, under a microscope or other detection device that permits detection of dyes. For instance, GFP Illuminators can be used, stereo microscopes for GFP observation can be used, fluorescence spectrometers can be used, and motic cameras can be used. These are merely several examples. A microscope can be used, wherein the microscope is either equipped with a fluorescent light or other means that will illuminate the dye if the dye is excitable such that analysis of the organic contaminants can easily be made.

For instance, once placed under a microscope or other device having fluorescence capability and wherein a fluorescent dye has been used, one can easily see, as shown in FIG. 1 herein, that organic contaminants are easily observable from other materials present in the pulp and fiber. Further, the pulp and fiber itself has not been significantly stained.

From observation, the amount of organic contaminants can be determined, the size of the contaminants can be determined, the surface area of the contaminants can be determined, and the like. Other characteristics of the organic contaminants that can be determined based on this method include, but are not limited to, surface morphology, surface color, and degree of contamination on stickies (i.e., ink particles, talc).

In addition, once the sample has been contacted with at least one hydrophobic dye and the organic contaminants stained, this sample, for instance, on a slide, can be subjected to computer analysis wherein a program can be used to analyze the staining and a computer program can calculate various characteristics of this sample, such as the surface area of the organic contaminants, the amount of the organic contaminants, and the like. The program can further inform the user of these characteristics, and the computer can further be programmed to determine the appropriate treatment that should be used to treat the organic contaminants based on this analysis. For instance, the computer program can determine what chemical treatment should be used, the amount of chemical treatment and/or the duration of the chemical treatment. Certainly, an individual with or without a computer program can make these observations, as well, simply based on a visual analysis of the stained sample.

With respect to the method of the present invention, the method to detect organic contaminants can be done on a continual basis, on a semi-continual basis, on a batch basis, or whenever there is a need to detect organic contaminants is desired. Any type of systematic analysis can be conducted in order to effectively monitor the amount of organic contaminants present in the pulp and fiber.

A purpose of the method of the present invention is to stain the organic contaminants (i.e., stickies) so they can be easily detected/seen/observed amongst fibers, regardless of fiber size, shape, species, etc. (long/short/hard/soft).

In addition, with the present invention, it is possible to see that different organic contaminants can be stained with different intensities. Thus, with the present invention, not only can the overall characteristics of the organic contaminants be understood, further, it is possible to understand the type of organic contaminants present, for instance, whether the contaminant has a certain percentage of ethylene vinyl acetate, styrene butadiene rubber, polyvinyl acetate, and the like. It has been determined through experiments that various organic contaminants will provide different intensities when viewed through the spectrometer or other observation device, such that determinations of the particular organic contaminants present can be understood. Based on observations of stickies under fluorescent light, it has been observed that different types of stickies have slightly different color(s). For example, polyvinyl acetate shows as “bright green” and styrene shows as “whiter-green.”

In the present invention, image analysis can be used to study the sample having the stained organic contaminants which can be done visually or with a computer program By this image analysis, size distribution, the amount of contaminants, and the like can be used. Further, this information can be made available to the papermill or other user by on-line techniques, by e-mails, or other electronic means which can provide such information. Although embodiments of the present invention are illustrated herein in terms of using fluorescent dyes, it will be appreciated that the concepts of the present invention are believed to have wider application using luminescence technology, such as phosphorescence, chemoluminescence or bioluminescence, triboluminescence, and other forms of luminescence.

The entire process of the present invention, including the analyses, can be completely automated.

The present invention will be further clarified by the following examples, which are intended to be exemplary of the present invention.

EXAMPLES Example 1

A fresh 1% w/w solution of a D4 stain (Dupont #4 dye, from E.I. DuPont de Nemours & Co.) in tap water was prepared. To ensure the complete dissolution of the stain, the solution was heated to almost boiling. 0.1 g (0.1 ml) of stock sample was placed into a test tube. 5 mls of D4 solution was added and the tube was put in hot, not boiling, water for 20 minutes. The contents of the test tube were poured onto a watch glass. A very small quantity of fibre and liquor was transferred onto a microscope slide. The slide was examined at ×40, ×100, ×400 magnification.

The sample appeared as a collection of red and green fibres with coloured and colourless particles distributed around the fibres. Stickies appear as amorphous, slightly rounded not angular particles. They can be either in the water phase or attached to a fibre.

Color Reaction SUBSTANCE COLOR WITH D4 STAIN Hardwood Fibre Red Softwood Fibre Green SBR Golden/Yellow PVA Dark Red/Maroon EVA Bright Yellow Polyacrylate Red/Pink

As can be seen from the above table, each organic contaminant has a different color, thus permitting one to determine the amount of each contaminant, besides knowing the overall amount of stickies present. Also, there is a direct correlation between the number of particles seen under the microscope at 40× to 150× and the problem seen on a paper machine.

Example 2

A procedure for enumerating microstickies was experimentally studied in a field application (i.e., an actual paper producing facility). This paper producing facility uses recovered post consumer papers as a raw material to produce a commercial paper product. In the past, this particular location has experienced operational problems due to stickies deposition on the paper machine equipment. These operational “outbreaks” (i.e. off-quality sheet due to holes, defects/contamination, PM breaks, reduced production, downtime, etc.) are costly. Moreover, these stickies-related outbreaks were not predicted in the past.

Table 1 below lists the excitation and emission wavelengths for the fluorescent tag/microstickies compound of these experiments. The data was generated using a Perkin-Elmer 150 Fluorescence Spectrophotometer with a Xenon Power Supply.

TABLE 1 Type of Adhesive Excitation Peak Emission Peak Comments Fluorescent TAG 466 536 (1% Solvent/Tag Mixture) Styrene Butadiene 464 532 Polyvinyl Acetate 460 530

At the onset of the evaluation, four sample locations in the paper production facility were selected for sampling, as follows:

PM headbox

PM WW

Krofta feed

Krofta accepts.

The following Table A describes the procedure used by the tester for microstickies detection and the enumeration method for these studies.

TABLE A Actual Microstickies Detection & Enumeration Method MATERIALS: Stereoscope equipped with UV ring light Large microscope glass slides (2 × 3 inches) Customized/etched fused silica (quartz) slide (2 × 3 inches) with ruling Britt Jar apparatus, equipped with 125 M (100 um) screen Millipore filter apparatus and vacuum connection/source Black Millipore Filter Paper 5-10 ml syringes Micropipette (for 1 ml extraction) Stickies Dye Solution 1,000 ML Glass Beaker, 200 ML Glass Beaker, One 10 ML Glass Beaker THIN STOCK (0.9& Consistency and less):  1. Turn Britt Jar on, set RPM at 1500  2. Pour 1000 ml headbox/pulp slurry into Britt Jar (Britt Jar equipped    with 125 M Size Screen, 100 um)  3. Run Britt Jar with pulp slurry run for 1 minute  4. Open Britt Jar drain for 2-3 second (to remove “head”)  5. Collect 100 ml of filtrate (in a clean, glass beaker. Save.)  6. Using a syringe, take 5 ml of the filtrate and place into a small glass    beaker  7. Using a micropipette, add 0.1 ml of the Stickies Dye to the filtrate    (5 ml)  8. Mix well with the tip of micropipette for 2-3 seconds (discard tip)  9. Using the Millipore filter apparatus (for water removal, pour the 5 ml    sample of treated filtrate into the funnel (make sure that    a black filter paper is in place) 10. Turn the vacuum on and drain (should take less than 5 seconds) 11. Carefully remove black filter paper sample from the Millipore Filter    Apparatus 12. Place the black filter paper onto a standard, glass microscope slide    (2 × 3 inches) 13. Carefully, place Crystal Cover Slide* on top of the black filter paper,    which contains the “treated sample” 14. Place the sample on the Stereo Scope mount 15. Turn the UV ring light on 16. Observe the sample at 2.5 Magnification 17. Count the number of stickies in each square (count 200 squares) 18. Report number as microstickies Notes: In lieu of an etched crystal slide, a preformed, wire mesh has been used. For stock solution (Consistency greater than .9%), the sample needs to be diluted down to headbox consistency. See calculation example below: Press: 25% Cons. Headbox: .65% Cons. For the Britt Jar (1,000 ml), 6.5 grams of fiber is needed. 6.5/.0025 = 26 grams of the Belt Press plus 1000 ml warm water

A series of tests were conducted in the paper production facility on different dates, designated herein as Test Nos. 1-15. The results for these tests are plotted in FIG. 2 and FIG. 3. FIG. 2 shows Krofta accepts and Krofia feed microstickies data for the tests. FIG. 3 shows PM headbox and PM WW microstickies data for the tests.

The data of the test results was analyzed using a statistics software program. Initial statistical analyses of the results suggest that the microstickies count in the PM WW correlates with some significance to at least the following:

Krofta accepts (microstickies).

Krofta accepts (NTU, both online and lab samples).

Fine screen (macrostickies).

DI storage (macrostickies).

Krofta feed (NTU, lab)—correlation is negative.

Similarly, the microstickies in the PM headbox sample correlate with some significance to at least the following:

Krofta feed microstickies.

Krofta accepts (online and lab sample).

In further studies, correlation between a PM outbreak of stickies and elevated microstickies counts was indicated. The microstickies count in the PM headbox sample increased to a level that alerted the tester. The following day, the higher than usual microstickies number in the PM WW sample alerted the tester as well. Finally, the macrostickies count also increased on this day (see Tables 2 and 3). Within the next 24-hour period, the paper machine experienced a stickies-related outbreak (stickies deposition). The count rose and remained elevated for two days. During that time, a sample of the deposit was removed from the paper machine and analyzed. The deposit contained PVA, also known as stickies, as confirmed by standard analysis. As a result of the machine deposition, the machine operator increased the dosage of OPTIMYZE® chemical (a process chemical used to control stickies deposition). The dosage was increased from to 22 cc/min to 32 cc/min. Approximately 12 days later, another spike in microstickies (PM WW and headbox samples) occurred; however, there was no stickies deposition on the paper machine.

TABLE 2 Microstickies Average Alerting Microstickies Count Microstickies Count Sample Prior to test date On test date PM Headbox 24 30 PM WW 8.8 15

TABLE 3 Average Microstickies Count Alerting Microstickies Count Sample Prior to test date On test date DI Storage 21 27

As a result of these tests, it was learned that the method itself of the present invention can yield repeatable, accurate results. One of the reasons for using this procedure is to make better predictions regarding paper machine operations. Other particular observations and conclusions reached from the tests results include the following:

-   -   This data (macrostickies) indicates that there is a correlation         between increased macrostickies counts and machine outbreaks.     -   Data (microstickies) also correlates to a machine upset.     -   The microstickies testing procedure is an indicator of potential         problems. If there are high microstickies counts, there is at         least a possibility that there could be an outbreak on the paper         machine.     -   The microstickies data indicates the high levels seen in the PM         system were at the time that the outbreak occurred.     -   There appears to be a correlation between higher microstickies         counts in the PM WW/PM headbox samples and actual stickies         deposition on the paper machine.     -   The procedure is easy to use in a mill setting.     -   The procedure appears to be repeatable/reliable.

These test results show the feasibility and advantages of embodiments of the present invention based on the introduction and utilization of a different type of light source (UV vs. visible) in combination with a fluorescent tagging agent. In general, in one or more embodiments, the present invention does not rely on the use of a dye (to impart color), but instead relies on a UV light source used in combination with a fluorescent tag. In this process, the tag reacts with the microstickies present in the sample (PVAc, SBR, etc). When the sample is exposed to a UV light source and viewed in a UV light source, the stickies/tag complex emits a strong optical fluorescent signal. Although other “background” components (i.e. talc, clay, fibers, starch, etc.) also absorb the fluorescent tag, the resulting optical signal emitting from these objects is considerably less intense than the signal emitting from the excited microstickies/dye complex. As a result, an operator/observer can easily view the microstickies. Ultimately, this technique diminishes false-positive recordings. By comparison, if dye(s)/pigments are used to differentiate the microstickies from other materials in a given sample by “color” when viewed with a visible light source, then, in that instance, it is difficult to differentiate between the colored microstickies and all the other colored objects (background noise), which leads to false-positive readings. In contrast thereto, this present invention focuses on the use of an alternative light source (UV) in combination with a fluorescent tag (which reacts specifically with microstickies). The result of viewing the sample in a UV light source is the emission of a superior optical signal, thereby diminishing false-positive recordings. Consequently, the inventive test procedure is easier for the operator to use, with results that are more repeatable and potentially more useful as a predictor/barometer for stickies outbreaks in paper machine systems.

It also will be appreciated that this example is only exemplary. The present invention can be practiced using different forms of luminescence. Luminescence is “light”, which is not generated from high temperatures alone. Non-limiting examples of luminescence in this regard include:

-   -   Photoluminescence (Fluorescence, Phosphorescence (Glow-in-the         Dark).     -   Chemoluminescence “Glow Sticks” (called Bioluminescence if in a         living cell (The Firefly).     -   Triboluminescence (Emission of “light” through application of         mechanical energy).

In the most general terms, luminescence technology could be used to help monitor, measure, and detect specific chemical products (commercialized enzymes), properties and attributes in various industrial processes. More importantly this technology of the present invention allows monitoring on line versus off line.

Example 3

Experimental evaluations were conducted on BULAB® 5453 bentonite (from Buckman Laboratories, Memphis Term.) to evaluate its performance in reducing the amount of suspend and colloidal material in the Krofta accepts, and specifically focusing on microstickies that were monitored and counted as part of the evaluation. The evaluation was run over a time period of four weeks, in which the BLLAB® 5453 Bentonite was substituted in production runs for an existing inorganic program used in the paper production facility, which was considered the “baseline” for purposes of these studies. The baseline material had been used and monitored in a prior four week production period. Microstickies were detected and enumerated in the manner described below.

The test results indicated that there was a 43% reduction in online turbidities when comparing the daily average turbidities for the baseline month when compared to the month long bentonite evaluation. In also conducting Krofta efficiencies, it was found that the overall removal efficiency of the Krofta efficiencies have been maintained at an 80% removal efficiency regardless of the inorganic component.

Results are shown in Table 4 below.

TABLE 4 Krofta Efficiencies: Baseline vs. Bentonite Trial Krofta Efficiency Baseline Bentonite Trial Krofta Feed (ppm) 376 393 Krofta Accepts (ppm)  73  78 Krofta Efficiency 81% 80%

Statistical analysis was run on the microstickies, Krofta turbidity, and production data to determine if there are correlations between them. The analysis shows the greatest statistical correlation with respect to the PM WW and Krofta (accepts) Turbidity, and the next strongest correlation was between the Krofta Accepts Microstickies and Krofia Accepts Turbidity. There was a discernible relationship between the paper machine break data and the microstickies data. There also was a reduction in microstickies circulating through the Krofta during the bentonite evaluation, a 17% reduction on Krofta Feed and an 18% reduction on Krofta accepts. The paper machine has also seen a reduction in microstickies, the headbox has had a 19% reduction in microstickies and the PM WW has had a 7% reduction.

Results are shown in Table 5 below.

TABLE 5 Microstickies Data Collection: Baseline vs. Bentonite Trial Microstickies Baseline Bentonite Trial % Change Krofta Feed (#) 4361 3600 −17% Krofta Accepts (#) 2200 1800 −18% PM WW (#) 2400 2225 −7% Headbox (#) 9938 8000 −19% *Units = Number of Microstickies per 1 L of Sample

The microstickies test procedure uses a 1 L sample that is treated with a specific dye; a smaller sample of the treated 1 L sample is then analyzed under the microscope to determine the microstickies count. When reporting the data, testers are extrapolating the microstickies count back to a 1 L sample size, which will provide a quantitative value that can be easily related back to the process. The microstickies data is displayed as the number of microstickies per 1 L of sample.

Macrostickies did increase during the bentonite evaluation, but it is believed the slight increase is attributed to the high deink production rates during the same time frame. There was a 27% increase of incoming macrostickies (from 8 to 11) during the bentonite evaluation, but there was only an 11% increase in macrostickies (from 23 to 26) in deink storage.

Results are shown in Table 6 below.

TABLE 6 Macrostickies Data Collection: Baseline vs. Bentonite Trial Macrostickies Baseline Bentonite Trial % Change Fine Screen Accepts (#) 8 11 26% Deink Storage (#) 23 26 14% *Units = Number of Macrostickies per 10 O.D. g F

Applicants specifically incorporate the entire contents of all cited references in this disclosure. Further, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.

Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the present specification and practice of the present invention disclosed herein. It is intended that the present specification and examples be considered as exemplary only with a true scope and spirit of the invention being indicated by the following claims and equivalents thereof. 

1. A method to detect organic contaminants in pulp and fiber comprising obtaining a sample of the pulp and fiber, and contacting said sample with at least one hydrophobic dye, wherein said hydrophobic dye stains the organic contaminants present in said sample.
 2. The method of claim 1, wherein said hydrophobic dye is a fluorescent hydrophobic dye.
 3. The method of claim 2, wherein said hydrophobic dye is Morplas blue.
 4. The method of claim 1, wherein said hydrophobic dye is a luminescence hydrophobic dye.
 5. The method of claim 1, wherein said hydrophobic dye is an excitable hydrophobic dye.
 6. The method of claim 1, wherein said pulp and fiber is not stained by said hydrophobic dye.
 7. The method of claim 1, wherein said organic contaminants have a size of 100 microns or less.
 8. The method of claim 1, further comprising removing organic contaminants having a size of greater than 100 microns prior to staining said sample.
 9. The method of claim 1, further comprising measuring the amount of organic contaminants that have been stained in said sample.
 10. The method of claim 9, wherein said measuring is achieved with a fluorescence spectrometer, GFP illuminator, or stereomicroscope, or motic camera.
 11. The method of claim 1, further comprising analyzing said sample having organic contaminants stained with at least one hydrophobic dye by digital analysis using a computer program.
 12. The method of claim 1, wherein organic contaminants comprise two or more different organic contaminants and said hydrophobic dye stains two or more different organic contaminants such that each organic contaminant emits a different color or shade color to distinguish organic contaminants from each other.
 13. A pulp and fiber sample comprising pulp and fiber and at least one organic contaminant stained by at least one hydrophobic dye.
 14. The pulp and fiber sample of claim 13, wherein said hydrophobic dye is a fluorescent hydrophobic dye. 